Combination heating, ventilating and air conditioning installations, such as that disclosed in DE-OS 24 45 590, are well known. Such installations typically comprise a housing and a blower for forcing air through and out of the housing. Downstream of the blower with regard to the direction of air flow there may be positioned an evaporator for air conditioning and a heater core. Several air outlet fittings are usually provided, each of which leads to an opening in the passenger compartment of the automobile. Control of the flow of air through the individual outlets is usually effected by pivoting baffles or the like. Such baffles are commonly regulated by means of a vacuum control element which, as the result of the restricted space available in passenger cars, must be positioned so that complex transmissions and lever translations are required. Such arrangements are very expensive because of the large number of individual parts and moreover are difficult to manufacture and install since they require the accurate alignment of baffles and associated adjusting mechanisms. A further disadvantage of baffle controlled air outlet openings is that, in vehicles having high air flow requirements, in order to maintain the desired level of heating and ventilation comfort, a large number of baffles and vacuum control elements must be provided.
Baffles actuated by means of vacuum control elements have an additional disadvantage in that most are generally either open or closed and cannot be opened into intermediate positions. While some vacuum controlled baffles may be brought into one intermediate position, they require the use of additional expensive control elements. In either case, the setting of an arbitrary number of intermediate baffle positions is not possible with the use of the vacuum control elements. Moreover, the known configurations require a considerable amount of valuable under-dashboard space, inasmuch as two heat exchangers, a blower and a plurality of closing and reversing baffles are all arranged in a common housing.